Forever I have been using the Properties>Security option to password protect CHANGING a document - allowing printing but disabling copy of text. I do NOT select password to open. But now sometimes in DC after I set the security as above it still asks people for password when opened. Although hitting cancel allows you in anyway. Weird. Its almost like when opening these problem PDFs it detects an instant change of some sort and asks for permission. But then lets cancel be used anyway in the password field. Any thoughts?
Sorry for the delay in response.
I just followed the steps you mentioned above using Acrobat DC with all the updates installed and it worked fine.
Securing PDFS with passwords, Adobe Acrobat Can you try after installing updates and let us know if that helps.